Method of making hot-water tanks



Sept. 4, 1945.

W. G. MARTIN METHOD OF MAKING HOT WATER TANKS Filed Feb. 16, 1942ATTORNEY.

atente Sept. 4, M45

T PATENT QFFICE METHOD OF MAKING HOT-WATER TANKS Application February16, 1942, Serial No. 431,042

Claims.

This invention relates to a method of making a hot water storage tankand more particularly to the method of making a hot water storage tankwhich is lined with fused ceramic enamel or other corrosion resistantprotective material, such as galvanizing, to protect the tank frominjury by corrosion while in use.

One object of the present invention is to provide a method of making atight fitting joint between the head and shell of a hot water storagetank.

Another object is to provide a method of constructing a lined hot watertank in which the joints between the heads and shell are strong anddurable, and not subject to undesirable deflection stresses in service.

Other objects of the invention will appar in the following descriptionof an embodiment of the invention illustrated in the accompanyingdrawing.

In the drawing:

Figure 1 is a longitudinal section of the completed hot water tankconstructed according to the method of the invention;

Fig. 2 is a longitudinal section of a shell and a punch and die appliedthereto for sizing the shell;

Fig. 3 is a perspective view of a head of a hot water tank, showing thesupporting member on which the head rests during the fusing of theceramic lining to the head;

Fig. 4 is a. longitudinal sectional view of a head and shell of a hotwater tank showing their position with respect to each other just priorto assembly and also showing in similar section the jigs for holding andsizing the head and shell during their assembly; and

Fig. 5 is an enlarged longitudinal section through a completed joint.

In constructing a hot water tank in accordance with the invention, theshell I is first fabricated by rolling or otherwise forming a suitablemetal blank into a cylinder and then welding the cylinder along itslongitudinally extending seam.

The metal blank employed is of a steel that has substantially uniformresidual stresses to thereby eliminate extensive warping when heated.The longitudinal welding of the seam of the cylinder is performed withconsiderable care to obtain an accurately'dimensioned circumference forthe shell.

Upon completion of the shell I as described, the end sections 2 of theshell are subjected to a sizing operation in a. device such as the punchand die 3, to true-up the ends of the shell into a substantiallycylindrical shape. This sizing operation should leave th respective endsof the shell with their circumference and diameter dimensionallyaccurate in order to properly receive the heads l and 5.

Th heads 4 .and 5 are fabricated in accurate dies from blanks of metalof a relatively heavier gauge than that employed in making the shell I.Any residual stresses therein are substantially uniformly distributed sothat ther is less tendency for warping when heated to fuse the liningthereon.

The heads are made from the blanks described, by forming them preferablywith convex crowns 6 and vertically flanged skirts I. In the formingoperation the skirts l are fabricated with an outside diameter onlysufilciently less than that of the inside diameter of the shell topermit insertion of the heads within the respective ends of the shell I,having regard to the thickness of the enamel. To obtain a tight fitbetween these members the dimensional tolerance limits of the heads andshell are maintained at a minimum.

After the construction of the shell I and the heads 4 and 5 has beencompleted as described, ceramic enameling material is applied to theirrespective interior surfaces, including the surfaces of the flangedskirts I of the heads, and fused in place to form the lining 8. Thelining 8 protects the interior surfaces of the heads and shell fromcorrosion by fluid contained in the tank in service.

The fusing of the ceramic enamel lining 8 to the interior of the shell Iis accomplished by subjecting the shell to a heating operation in whichthe lining and shell are heated to about 1600 F. In this operation theshell is placed upright in a heating furnace. Th only portion of thefurnace engaged by the shell is the floor or support contacted by thesupporting end of the shell. This endwise vertical placement preventsany substantial sagging of the shell by the heat to which it-issubjected.

The fusing of the ceramic enamel to the heads 4 and 5 is performed as inthe case of the shell I, by subjecting the heads to a heating operation.The heads are specially supported in the heating furnace by a supportmember 9 that preferably contacts each respective head at four distinctpoints. The support member is formed generally in the shape of an X andeach respective head is placed on an X support 9 in such a manner thatthe ceramic lining 8 faces upwardly and the ends of the flanges I engagethe support member 9 at four circumferentially spaced points asillustrated in Fig. 3. In this position the crowns 6, constituting thebodies of the heads are suspended and held away from the supportingmember 9 during the heating of the heads to fusing temperatures. Thismode of supporting the heads prevents any substantial warping ordeformation of them by the heat that is required to fuse the ceramicenamel lining 8 to their interior surfaces.

After the fusing operations for one or more coatings of enamel arcompleted, the shell I and heads 4 and are inspected for possibledefects in the lining 8. Since the assembly of the head 4 with the shellI .is preferably similar to that of the head 5 therewith, it issuflicient hereafter to limit the description to the assembly of thehead 4 'with the shell I.

In assembling the members of the tank, the shell I is first placedwithin the jig III which preferably consists of two complementarymembers having semi-cylindrical openings to fit the shell, a illustratedin Fig. 4, and any quick operating mechanism, not shown, to close themembers around the shell. The jig l0 holds the shell I circular and inalignment'with the head 4 as they are assembled together.

The head 4 is preferably held by the jig II, as illustrated in Fig. 4,the latter having means secured in a spud Or other suitable opening inthe head for supporting and moving the head. The jig axially aligns thehead 4 with the shell I and maintains this alignment during the assemblyof the two members.

As the shell i and the head 4 are held in the jigs i0 and IIrespectively, as described, the head 4 is inserted in the end of theshell and subjected to axial pressure to obtain a tight fit between theflanged skirt 1 of the head and the end section 2 of the shell with thelining 8 of each member concentrically overlapping one another for asubstantial distance and the edges of the shell and skirt flush. Whilethe head and shell are held in this position the seam extendingcircumferentially around the edges of the shell and the skirt of thehead is welded in any suitable manner, preferably by the electric arcmethod in which the metal of the respective edges of the ,members ismelted and fused together.

It is preferred that the end of the head be disposed flush with the endof the shell as illustrated by Figs. 1 and 5. However, an angular seammay be provided between the head and shell by disposing'the head so thatthe end projects slightly outwardly from the end of the shell.

A close control of the dimensional tolerances of the head 4 and theshell I and the sizing and assembly of these members in the mannerdescribed provides a tight fit in the joint between the shell and headwithout requiring the use of a gasket. In the event that any liquidcontained in the tank contacts exposed metal at th joint between thehead and shell, the products of corrosion will quickly fill any spacethat may exist between the linings 8eof the skirt 1 of the head and theend section 2 of the shell to effectively prevent any further access offluid to the Joint.

A similar function may also be performed by a thin corrosion resistantpliable material disposed in the joint between the overlapping parts ofthe head and shell.

The tanks made in accordance with the invention have strong and durablejoints and the invention may readily be applied to the joining togetherof numerous kinds of liquid or fluid containers.

Various embodiments of the invention may be employed within the scope ofthe accompanying claims.

I claim:

1. In the manufacture and assembly of a hot water storage tank having agenerally cylindrical shell and a head to close one end of said shell,the steps comprising sizing said shell to provide the same with anaccurately determined internal circumference, lining the interiorsurface of the shell and head with a corrosion resistant material toprotect the same from corrosion, thereafter applying a jig to the end ofsaid shell to bring it into substantially circular section and holdingit therein while inserting the head into the end of the shell with theend section of the head tightly fitting concentrically within andoverlapping the end of the shell for a substantial distance, andcircumferentially sealing the tank by welding the joint between the headand shell.

2. In the manufacture and assembly of a hot water storage tank having agenerally cylindrical shell and a flanged head to close an end of sadshell, the steps comprising lining said shell and head with ceramicenameling material, heating the shell while supported on end to a fusingtemperature for the enamel to bond the same to the wall of the shell,supporting said head on the end of its flange and heating the same to afusing temperature for the enamel to bond the same to the wall of thehead, thereafter applying a jig to the end of the shell to bring thesame into more accurate circular shape for receiving the head,circumferentially aligning the shell and head while inserting the headinto the end of the shell with the flange of the head tightly flttingconcentrically within and overlapping the end of the shell for asubstantial distance, and circumferentially sealing the tank by weldingthe .1 oint between the head and shell.

3. The method of making and assembling a hot water tank or likecontainer, comprising forming a cylindrical shell from a sheet metalblank, welding the longitudinal meeting edges of the shell, subjectingthe end portion of the shell to a cylindrical sizing operation toaccurately determine the internal circumference thereof, forming an endhead between accurately dimensioned dies to provide an end closure forsaid shell, said head having a substantially cylindrical circumferentialflange with an outside circumference slightly less than the insidecircumference of the end of said shell, lining said shell and said headwith ceramic enameling material, heating the cylindrical shell whilesupported on end to a high temperature effecting fusing of the enamelingmaterial'and bond ng of the same to the wall of the shell, supportingsaid head on the edge of said flange and heating the same to a hightemperature effecting fusion of the enameling material and bonding ofthe same to the head, applying a jig to the end of said shell to bringit into substantially circular section and holding it therein whileinserting the head into the end of the shell with the flange on the headtightly fltting within the shell and having its edge extending in thedirection of the end edge of the shell, the lining of the flange of thehead overlapping the lining of the end of the shell in tight engagementfor a substantial longitudinal distance, and circumferentially weldingthe edge portion of said flange and the end of the shell together toprovide a joint withstanding the fluid pressure within the tank inservice.

4. The method of making and assembling a hot water tank or likecontainer, comprisng forming a cylindrical shell from a sheet metalblank, welding the longitudinal meeting edges of the shell, subjectingthe end portion of the shell to a cylindrical sizing operation toaccurately determine the circumference thereof, forming an end headbetween accurately dimensioned dies to provide an end closure for saidshell, said head having a substantially cylindrical circumferentialflange with an outside circumference slightly less than the insidecircumference of the end of said shell, lining said shell and said headwith ceramic enameling material, heating the cylindrical shell whilesupported on end to a high temperature eflecting fusing of the enamelingmaterial and bonding of the same to the wall of the shell, supportingsaid head on the edge of said flange and heating the same to a hightemperature effecting fusion of the enameling material and bonding ofthe same to the head, applying a jig to the end of said shell to bringit into substantially circular section and holding it therein whileinserting the head into the end of the shell with the flange on the headtightly fitting within the shell and having its edge extending in thedirection of the end edge of the shell, the lining of the flange of thehead overlapping the lining of the end of the shell in tight engagementfor a substantial longitudinal distance, circumferentially welding theedge portion of said flan e and the end of the shell together to providea joint withstanding the fluid pressure within the tank in service, andheating the end portion of the tank to fuse the enamel linings togetheradjacent the weld to protect the latter from corrosion.

5. The method of making and assembling a hot water tank or likecontainer comprising forming acylindrical shell from a sheet metalblank, welding the longitudinal meeting edges of the .shell, subjectingthe shell to a cylindrical sizing operation to accurately determine thecircumference thereof, forming an end head between accuratelydimensioned dies to provide an end closure for said shell, said headhaving a substantially cylindrical circumferential flange with anoutside circumference slightly less than the inside circumference of theend of the shell, lining said shell and said head with ceramic enamelingmaterial, heating the cylindrical shell while supported on end to a hightemperature effecting fusing of the enameling material and bonding ofthe same to the wall of the shell, supporting said head on the end ofsaid flange and heating the same to a high temperature effecting fusionof the enameling material and bonding of the same to the head,circumferentially aligning the shell and head as the latter is insertedin one end or the shell with the enamel coatings in tight contact, andwelding the adjacent edges together to provide a tightly fitting joint,the heat of the welding operation fusing together the linings of thehead and shell adjacent the joint to protect the metal at the joint fromcorrosion.

WESLEY G. MARTIN.

